Irrigation Engineering and Hydraulic Structures

Description

Irrigation is the science of supplying water to the cultivated land in accordance with the varying requirements of the crops grown therein. Assured irrigation is found to have increased the productivity of unirrigated (rain-fed) land by as much as five times; say from about 0.5 t/ha to about 2.5 t/ha in a tropical country like India, which makes irrigation as an absolute necessity for our country. Although India receives sufficient quantity of about 4000 b.cum of average annual precipitation, resulting in 1869 cum of average annual runoff, yet about 85% of this fresh water supply isreceived in only four monsoon months, whereas water is required throughout the year, necessitating development of sufficient surface as well as underground storages during rainy season for subsequent uses during lean season. Out of the estimated average annual utilizable flow of 1122 b.cum, the present utilization, however, is only about 630 b.cum; (i/c 200 b.cum of ground water) out of which, about 500 b.cum (i.e. about 80%) is being used for irrigation alone. Even with such a huge percentage of the total utilized water being supplied for irrigation, we are just able to irrigate only about 45% of our gross cropped area of 190 Mha, with a created irrigation potential of about 100 Mha, as against the ultimate potential of 140 Mha, which can be developed with ordinary in-basin storages, without involving inter basin water transfers, which may further help in creating an additional irrigation potential of 35 Mha. Besides minimizing the use of irrigation water by adopting canal linings, sprinkler irrigation and micro-irrigation techniques such as drip irrigation on a large scale, additional waters are still required to be developed (stored) for bringing additional cropped area under irrigation to increase our food and fiber production, to fulfill our growing demands for ever increasing population. The techniques which are deployed for construction of an efficiently functioning irrigation system have been lucidly explained in this popular book. Besides covering irrigation in general, the book covers the Design & Construction of Canals and Canal structures, like Barrages, Canal falls, Canal outlets, Cross-drainage works, Bridges and Culverts, etc.; the Storage Reservoirs and Dams have also been extensively covered. Use of groundwater for irrigation, and development of Hydropower have also be dealt in details. The text matter has been further supported with more than 600 Objective Questions, including those from the various competitive examinations. The prestigious UPSC competitions continue to carry questions from this book year after year.